/*
*  linux/fs/read_write.c
*
*  (C) 1991  Linus Torvalds
*/

#include <sys\stat.h>
#include <errno.h>
#include <sys\types.h>

#include <linux\kernel.h>
#include <linux\sched.h>
#include <asm\segment.h>

extern int rw_char(int rw, int dev, char * buf, int count, off_t * pos);
extern int read_pipe(struct m_inode * inode, char * buf, int count);
extern int write_pipe(struct m_inode * inode, char * buf, int count);
extern int block_read(int dev, off_t * pos, char * buf, int count);
extern int block_write(int dev, off_t * pos, char * buf, int count);
extern int file_read(struct m_inode * inode, struct file * filp,
	char * buf, int count);
extern int file_write(struct m_inode * inode, struct file * filp,
	char * buf, int count);

int sys_lseek(unsigned int fd, off_t offset, int origin)
{
	struct file * file;
	int tmp;

	if (fd >= NR_OPEN || !(file = current->filp[fd]) || !(file->f_inode)
		|| !IS_SEEKABLE(MAJOR(file->f_inode->i_dev)))
		return -EBADF;
	if (file->f_inode->i_pipe)
		return -ESPIPE;
	switch (origin) {
	case 0:
		if (offset < 0) return -EINVAL;
		file->f_pos = offset;
		break;
	case 1:
		if (file->f_pos + offset < 0) return -EINVAL;
		file->f_pos += offset;
		break;
	case 2:
		if ((tmp = file->f_inode->i_size + offset) < 0)
			return -EINVAL;
		file->f_pos = tmp;
		break;
	default:
		return -EINVAL;
	}
	return file->f_pos;
}

int sys_read(unsigned int fd, char * buf, int count)
{
	struct file * file;
	struct m_inode * inode;

	if (fd >= NR_OPEN || count < 0 || !(file = current->filp[fd]))
		return -EINVAL;
	if (!count)
		return 0;
	verify_area(buf, count);
	inode = file->f_inode;
	if (inode->i_pipe)
		return (file->f_mode & 1) ? read_pipe(inode, buf, count) : -EIO;
	if (S_ISCHR(inode->i_mode))
		return rw_char(READ, inode->i_zone[0], buf, count, &file->f_pos);
	if (S_ISBLK(inode->i_mode))
		return block_read(inode->i_zone[0], &file->f_pos, buf, count);
	if (S_ISDIR(inode->i_mode) || S_ISREG(inode->i_mode)) {
		if (count + file->f_pos > inode->i_size)
			count = inode->i_size - file->f_pos;
		if (count <= 0)
			return 0;
		return file_read(inode, file, buf, count);
	}
	printk("(Read)inode->i_mode=%06o\n\r", inode->i_mode);
	return -EINVAL;
}

int sys_write(unsigned int fd, char * buf, int count)
{
	struct file * file;
	struct m_inode * inode;

	if (fd >= NR_OPEN || count < 0 || !(file = current->filp[fd]))
		return -EINVAL;
	if (!count)
		return 0;
	inode = file->f_inode;
	if (inode->i_pipe)
		return (file->f_mode & 2) ? write_pipe(inode, buf, count) : -EIO;
	if (S_ISCHR(inode->i_mode))
		return rw_char(WRITE, inode->i_zone[0], buf, count, &file->f_pos);
	if (S_ISBLK(inode->i_mode))
		return block_write(inode->i_zone[0], &file->f_pos, buf, count);
	if (S_ISREG(inode->i_mode))
		return file_write(inode, file, buf, count);
	printk("(Write)inode->i_mode=%06o\n\r", inode->i_mode);
	return -EINVAL;
}
